This invention relates to the field of ink jet printers. More particularly, this invention relates to an improved ink jet printer ink cartridge and ink cartridge body carrier and a method for alignment of the ink cartridge body relative to a print media.
There are a variety of factors which ultimately determine the print quality obtained from an ink jet printer. However, the position and alignment of the printheads relative to the print media is one of the most important factors to be taken into account when designing a printer. The printheads include a number of nozzles which expel ink based on input image data fed into the printer. If the printheads are not aligned and positioned properly, the resulting printed image may not reflect the true image that is inputted into the printer for printing. Therefore, there is a need to provide an ink jet printer having printheads that are aligned and positioned within an ink jet printer to produce a high-quality replica of the input image data.
Alignment of the printheads to the print media is conventionally achieved indirectly by means of an aligned carriage. The carriage provides a dual-purpose function within the ink jet printer. First, the carriages provide secure connection of the printheads to the printer. More importantly, however, the carriage is aligned in the printer to provide indirect alignment and positioning of the printheads relative to the print media to ensure a quality printed image.
Accordingly, such carriages include bearing and alignment surfaces located on the carriage body for translating the carriage attached printheads back and forth along guide rails within the printer. The back and forth carriage translation enables the printheads to expel ink at various locations on the print media. Alignment of the printheads to the carriage is also important for print quality. The carriage and printheads therefore include a number of tolerances that a manufacturer must pay careful attention to when manufacturing the printer and associated printer components. If one or more of these tolerances are not adhered to, there can be a serious deterioration in the ink jet printer print quality. What is needed, therefore, is a means to reduce the number of tolerances associated with printhead alignment relative to a print media within an ink jet printer without adversely affecting print quality.
With regard to the foregoing and other objects, the present invention is directed to a unique ink cartridge body and cartridge body translation mechanism which reduces the number of tolerances required for printhead alignment in an ink jet printer.
The foregoing and other needs are provided by an improved ink jet printer ink cartridge body. The ink cartridge body is removably mountable in a printer carriage area of an ink jet printer. The printer carriage area includes at least first and second spaced-apart elongate guide rails. The ink cartridge body is provided by a molded or cast structure having an open-ended cavity therein for slidably engaging at least one ink cartridge. At least one printhead is fixedly attached in a printhead location on the ink cartridge body opposite the open-ended cavity. A cartridge body translation mechanism is attached to the cartridge body for translating the cartridge body in the printer carriage area relative to the elongate guide rails. At least two bearing points are provided at predetermined locations on the ink cartridge body, each of the bearing points being disposed on the cartridge body for separately engaging at least one of the elongate guide rails for aligning and maintaining the printhead in a predetermined orientation relative to the print media in the printer.
This invention also provides a method for aligning at least one printhead of an ink jet printer. The method includes providing an ink cartridge body which is removably mountable in a printer carriage area of an ink jet printer. The ink cartridge body is a molded or cast structure having an open-ended cavity therein for slidably engaging at least one ink cartridge and contains at least one printhead fixedly attached in a printhead location on the ink cartridge body opposite the open-ended cavity. At least two bearing points are disposed at a first end and a second end of the ink cartridge body for locating the ink cartridge body relative to first and second spaced-apart elongate guide rails. The bearing points engage the first and second guide rails in the printer carrier area of the ink jet printer. A printhead translation mechanism is attached to the cartridge body. The bearing points are positioned on the elongate guide rails so that the ink cartridge body is substantially supported by the elongate guide rails and aligned relative to print media and the printhead translation mechanism is substantially unsupported by the elongate guide rails.
An advantage of the present invention includes substantially improved print quality which is effected by reducing the number of tolerances required to align the ink jet printheads with respect to the print media. Another advantage of the invention that the ink cartridge body itself is transported along the elongate guide rails with improved dynamic stability. Bearings on the cartridge body rather than the carrier provide dynamic alignment of the printheads in the printer while the cartridge body is being translated along the length of the elongate guide rails. An important feature of the invention is the elimination of a conventional carrier which contains alignment tolerances to which a printhead body is attached. Instead of a carrier being attached to and aligned with the elongate guide rails, the printhead body itself is in direct contact with and aligned relative to the guide rails. The carrier, which is attached to the printhead body, is substantially unsupported by the guide rails. xe2x80x9cSubstantially unsupportedxe2x80x9d means that carrier contains no bearing surfaces or other surfaces in direct contact with the guide rails.